Technical Field
This disclosure relates to wireless communication systems and more particularly to multiple input, multiple output (MIMO) communications.
Description of the Related Art
Modern communication systems rely upon multiple antennas at the transmitter and/or receiver to enhance link performance. This class of techniques, known as multiple input, multiple output (MIMO) exploits the spatial dimension by employing spatial encoding and/or decoding. Massive MIMO is an exciting theoretical area of 5G wireless that promises significant gains that offer the ability to accommodate more users, at higher data rates, with better reliability, while consuming less power. Conventional MIMO base stations typically use six or eight antennas in a sectorized topology, but massive MIMO base stations utilize more than eight antennas (and sometimes as many as 128, 256, or more) while massive MIMO user equipment devices (UEs) may typically utilize around eight antennas. Using the larger number of antenna elements, massive MIMO reduces power in a given channel by focusing the energy to targeted mobile users using precoding techniques. By directing the wireless energy to specific users, the power in channel is reduced and, at the same time, interference to other users is decreased.
The introduction of so many antenna elements, however, introduces several system challenges not encountered in conventional networks. For example, conventional data networks may use LTE or LTE-Advanced, which in turn use the pilot tones in an orthogonal frequency division multiplexing (OFDM) waveform to estimate the channel condition. With many antennas and transmitters, a massive MIMO system, may essentially run out of unique pilot tones for a receiver to effectively detect and resolve channel conditions. Further, processing and synchronization requirements for massive MIMO may be difficult to meet using conventional systems.
Therefore both test systems for prototyping different MIMO techniques and approaches and production MIMO systems configured to utilize these techniques are desired.